This invention relates to a bias magnetic field generating apparatus usable in magneto-optical recording and reproducing systems.
Magneto-optical disks (Opto-magnetic disks) have been widely used as information recording media for computers. During the writing of information into a magneto-optical disk or the erasion of information from the disk, it is necessary to apply a bias magnetic field of a given strength or greater to the disk along a direction perpendicular to a recording surface of the disk. In addition, it is necessary to invert the polarity of the bias magnetic field between the information writing period and the information erasing period.
As will be explained later, a prior art apparatus for generating such a bias magnetic field has some problems.